hwmon: add generic GPIO fan driver

This patch adds hwmon support for fans connected to GPIO lines.

Platform specific information such as GPIO pinout and speed conversion array
(rpm from/to GPIO value) are passed to the driver via platform_data.

Signed-off-by: Simon Guinot <sguinot@lacie.com>
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

1 files changed, 558 insertions, 0 deletions

diff --git a/drivers/hwmon/gpio-fan.c b/drivers/hwmon/gpio-fan.c
new file mode 100644
index 000000000000..aa701a183707
--- /dev/null
+++ b/drivers/hwmon/gpio-fan.c
@@ -0,0 +1,558 @@
+/*
+ * gpio-fan.c - Hwmon driver for fans connected to GPIO lines.
+ *
+ * Copyright (C) 2010 LaCie
+ *
+ * Author: Simon Guinot <sguinot@lacie.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/platform_device.h>
+#include <linux/err.h>
+#include <linux/mutex.h>
+#include <linux/hwmon.h>
+#include <linux/gpio.h>
+#include <linux/gpio-fan.h>
+
+struct gpio_fan_data {
+        struct platform_device  *pdev;
+        struct device           *hwmon_dev;
+        struct mutex            lock; /* lock GPIOs operations. */
+        int                     num_ctrl;
+        unsigned                *ctrl;
+        int                     num_speed;
+        struct gpio_fan_speed   *speed;
+        int                     speed_index;
+#ifdef CONFIG_PM
+        int                     resume_speed;
+#endif
+        bool                    pwm_enable;
+        struct gpio_fan_alarm   *alarm;
+        struct work_struct      alarm_work;
+};
+
+/*
+ * Alarm GPIO.
+ */
+
+static void fan_alarm_notify(struct work_struct *ws)
+{
+        struct gpio_fan_data *fan_data =
+                container_of(ws, struct gpio_fan_data, alarm_work);
+
+        sysfs_notify(&fan_data->pdev->dev.kobj, NULL, "fan1_alarm");
+        kobject_uevent(&fan_data->pdev->dev.kobj, KOBJ_CHANGE);
+}
+
+static irqreturn_t fan_alarm_irq_handler(int irq, void *dev_id)
+{
+        struct gpio_fan_data *fan_data = dev_id;
+
+        schedule_work(&fan_data->alarm_work);
+
+        return IRQ_NONE;
+}
+
+static ssize_t show_fan_alarm(struct device *dev,
+                              struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+        struct gpio_fan_alarm *alarm = fan_data->alarm;
+        int value = gpio_get_value(alarm->gpio);
+
+        if (alarm->active_low)
+                value = !value;
+
+        return sprintf(buf, "%d\n", value);
+}
+
+static DEVICE_ATTR(fan1_alarm, S_IRUGO, show_fan_alarm, NULL);
+
+static int fan_alarm_init(struct gpio_fan_data *fan_data,
+                          struct gpio_fan_alarm *alarm)
+{
+        int err;
+        int alarm_irq;
+        struct platform_device *pdev = fan_data->pdev;
+
+        fan_data->alarm = alarm;
+
+        err = gpio_request(alarm->gpio, "GPIO fan alarm");
+        if (err)
+                return err;
+
+        err = gpio_direction_input(alarm->gpio);
+        if (err)
+                goto err_free_gpio;
+
+        err = device_create_file(&pdev->dev, &dev_attr_fan1_alarm);
+        if (err)
+                goto err_free_gpio;
+
+        /*
+         * If the alarm GPIO don't support interrupts, just leave
+         * without initializing the fail notification support.
+         */
+        alarm_irq = gpio_to_irq(alarm->gpio);
+        if (alarm_irq < 0)
+                return 0;
+
+        INIT_WORK(&fan_data->alarm_work, fan_alarm_notify);
+        set_irq_type(alarm_irq, IRQ_TYPE_EDGE_BOTH);
+        err = request_irq(alarm_irq, fan_alarm_irq_handler, IRQF_SHARED,
+                          "GPIO fan alarm", fan_data);
+        if (err)
+                goto err_free_sysfs;
+
+        return 0;
+
+err_free_sysfs:
+        device_remove_file(&pdev->dev, &dev_attr_fan1_alarm);
+err_free_gpio:
+        gpio_free(alarm->gpio);
+
+        return err;
+}
+
+static void fan_alarm_free(struct gpio_fan_data *fan_data)
+{
+        struct platform_device *pdev = fan_data->pdev;
+        int alarm_irq = gpio_to_irq(fan_data->alarm->gpio);
+
+        if (alarm_irq >= 0)
+                free_irq(alarm_irq, fan_data);
+        device_remove_file(&pdev->dev, &dev_attr_fan1_alarm);
+        gpio_free(fan_data->alarm->gpio);
+}
+
+/*
+ * Control GPIOs.
+ */
+
+/* Must be called with fan_data->lock held, except during initialization. */
+static void __set_fan_ctrl(struct gpio_fan_data *fan_data, int ctrl_val)
+{
+        int i;
+
+        for (i = 0; i < fan_data->num_ctrl; i++)
+                gpio_set_value(fan_data->ctrl[i], (ctrl_val >> i) & 1);
+}
+
+static int __get_fan_ctrl(struct gpio_fan_data *fan_data)
+{
+        int i;
+        int ctrl_val = 0;
+
+        for (i = 0; i < fan_data->num_ctrl; i++) {
+                int value;
+
+                value = gpio_get_value(fan_data->ctrl[i]);
+                ctrl_val |= (value << i);
+        }
+        return ctrl_val;
+}
+
+/* Must be called with fan_data->lock held, except during initialization. */
+static void set_fan_speed(struct gpio_fan_data *fan_data, int speed_index)
+{
+        if (fan_data->speed_index == speed_index)
+                return;
+
+        __set_fan_ctrl(fan_data, fan_data->speed[speed_index].ctrl_val);
+        fan_data->speed_index = speed_index;
+}
+
+static int get_fan_speed_index(struct gpio_fan_data *fan_data)
+{
+        int ctrl_val = __get_fan_ctrl(fan_data);
+        int i;
+
+        for (i = 0; i < fan_data->num_speed; i++)
+                if (fan_data->speed[i].ctrl_val == ctrl_val)
+                        return i;
+
+        dev_warn(&fan_data->pdev->dev,
+                 "missing speed array entry for GPIO value 0x%x\n", ctrl_val);
+
+        return -EINVAL;
+}
+
+static int rpm_to_speed_index(struct gpio_fan_data *fan_data, int rpm)
+{
+        struct gpio_fan_speed *speed = fan_data->speed;
+        int i;
+
+        for (i = 0; i < fan_data->num_speed; i++)
+                if (speed[i].rpm >= rpm)
+                        return i;
+
+        return fan_data->num_speed - 1;
+}
+
+static ssize_t show_pwm(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+        u8 pwm = fan_data->speed_index * 255 / (fan_data->num_speed - 1);
+
+        return sprintf(buf, "%d\n", pwm);
+}
+
+static ssize_t set_pwm(struct device *dev, struct device_attribute *attr,
+                       const char *buf, size_t count)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+        unsigned long pwm;
+        int speed_index;
+        int ret = count;
+
+        if (strict_strtoul(buf, 10, &pwm) || pwm > 255)
+                return -EINVAL;
+
+        mutex_lock(&fan_data->lock);
+
+        if (!fan_data->pwm_enable) {
+                ret = -EPERM;
+                goto exit_unlock;
+        }
+
+        speed_index = DIV_ROUND_UP(pwm * (fan_data->num_speed - 1), 255);
+        set_fan_speed(fan_data, speed_index);
+
+exit_unlock:
+        mutex_unlock(&fan_data->lock);
+
+        return ret;
+}
+
+static ssize_t show_pwm_enable(struct device *dev,
+                               struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%d\n", fan_data->pwm_enable);
+}
+
+static ssize_t set_pwm_enable(struct device *dev, struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+        unsigned long val;
+
+        if (strict_strtoul(buf, 10, &val) || val > 1)
+                return -EINVAL;
+
+        if (fan_data->pwm_enable == val)
+                return count;
+
+        mutex_lock(&fan_data->lock);
+
+        fan_data->pwm_enable = val;
+
+        /* Disable manual control mode: set fan at full speed. */
+        if (val == 0)
+                set_fan_speed(fan_data, fan_data->num_speed - 1);
+
+        mutex_unlock(&fan_data->lock);
+
+        return count;
+}
+
+static ssize_t show_pwm_mode(struct device *dev,
+                             struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "0\n");
+}
+
+static ssize_t show_rpm_min(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%d\n", fan_data->speed[0].rpm);
+}
+
+static ssize_t show_rpm_max(struct device *dev,
+                            struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%d\n",
+                       fan_data->speed[fan_data->num_speed - 1].rpm);
+}
+
+static ssize_t show_rpm(struct device *dev,
+                        struct device_attribute *attr, char *buf)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+
+        return sprintf(buf, "%d\n", fan_data->speed[fan_data->speed_index].rpm);
+}
+
+static ssize_t set_rpm(struct device *dev, struct device_attribute *attr,
+                       const char *buf, size_t count)
+{
+        struct gpio_fan_data *fan_data = dev_get_drvdata(dev);
+        unsigned long rpm;
+        int ret = count;
+
+        if (strict_strtoul(buf, 10, &rpm))
+                return -EINVAL;
+
+        mutex_lock(&fan_data->lock);
+
+        if (!fan_data->pwm_enable) {
+                ret = -EPERM;
+                goto exit_unlock;
+        }
+
+        set_fan_speed(fan_data, rpm_to_speed_index(fan_data, rpm));
+
+exit_unlock:
+        mutex_unlock(&fan_data->lock);
+
+        return ret;
+}
+
+static DEVICE_ATTR(pwm1, S_IRUGO | S_IWUSR, show_pwm, set_pwm);
+static DEVICE_ATTR(pwm1_enable, S_IRUGO | S_IWUSR,
+                   show_pwm_enable, set_pwm_enable);
+static DEVICE_ATTR(pwm1_mode, S_IRUGO, show_pwm_mode, NULL);
+static DEVICE_ATTR(fan1_min, S_IRUGO, show_rpm_min, NULL);
+static DEVICE_ATTR(fan1_max, S_IRUGO, show_rpm_max, NULL);
+static DEVICE_ATTR(fan1_input, S_IRUGO, show_rpm, NULL);
+static DEVICE_ATTR(fan1_target, S_IRUGO | S_IWUSR, show_rpm, set_rpm);
+
+static struct attribute *gpio_fan_ctrl_attributes[] = {
+        &dev_attr_pwm1.attr,
+        &dev_attr_pwm1_enable.attr,
+        &dev_attr_pwm1_mode.attr,
+        &dev_attr_fan1_input.attr,
+        &dev_attr_fan1_target.attr,
+        &dev_attr_fan1_min.attr,
+        &dev_attr_fan1_max.attr,
+        NULL
+};
+
+static const struct attribute_group gpio_fan_ctrl_group = {
+        .attrs = gpio_fan_ctrl_attributes,
+};
+
+static int fan_ctrl_init(struct gpio_fan_data *fan_data,
+                         struct gpio_fan_platform_data *pdata)
+{
+        struct platform_device *pdev = fan_data->pdev;
+        int num_ctrl = pdata->num_ctrl;
+        unsigned *ctrl = pdata->ctrl;
+        int i, err;
+
+        for (i = 0; i < num_ctrl; i++) {
+                err = gpio_request(ctrl[i], "GPIO fan control");
+                if (err)
+                        goto err_free_gpio;
+
+                err = gpio_direction_output(ctrl[i], gpio_get_value(ctrl[i]));
+                if (err) {
+                        gpio_free(ctrl[i]);
+                        goto err_free_gpio;
+                }
+        }
+
+        err = sysfs_create_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
+        if (err)
+                goto err_free_gpio;
+
+        fan_data->num_ctrl = num_ctrl;
+        fan_data->ctrl = ctrl;
+        fan_data->num_speed = pdata->num_speed;
+        fan_data->speed = pdata->speed;
+        fan_data->pwm_enable = true; /* Enable manual fan speed control. */
+        fan_data->speed_index = get_fan_speed_index(fan_data);
+        if (fan_data->speed_index < 0) {
+                err = -ENODEV;
+                goto err_free_gpio;
+        }
+
+        return 0;
+
+err_free_gpio:
+        for (i = i - 1; i >= 0; i--)
+                gpio_free(ctrl[i]);
+
+        return err;
+}
+
+static void fan_ctrl_free(struct gpio_fan_data *fan_data)
+{
+        struct platform_device *pdev = fan_data->pdev;
+        int i;
+
+        sysfs_remove_group(&pdev->dev.kobj, &gpio_fan_ctrl_group);
+        for (i = 0; i < fan_data->num_ctrl; i++)
+                gpio_free(fan_data->ctrl[i]);
+}
+
+/*
+ * Platform driver.
+ */
+
+static ssize_t show_name(struct device *dev,
+                         struct device_attribute *attr, char *buf)
+{
+        return sprintf(buf, "gpio-fan\n");
+}
+
+static DEVICE_ATTR(name, S_IRUGO, show_name, NULL);
+
+static int __devinit gpio_fan_probe(struct platform_device *pdev)
+{
+        int err;
+        struct gpio_fan_data *fan_data;
+        struct gpio_fan_platform_data *pdata = pdev->dev.platform_data;
+
+        if (!pdata)
+                return -EINVAL;
+
+        fan_data = kzalloc(sizeof(struct gpio_fan_data), GFP_KERNEL);
+        if (!fan_data)
+                return -ENOMEM;
+
+        fan_data->pdev = pdev;
+        platform_set_drvdata(pdev, fan_data);
+        mutex_init(&fan_data->lock);
+
+        /* Configure alarm GPIO if available. */
+        if (pdata->alarm) {
+                err = fan_alarm_init(fan_data, pdata->alarm);
+                if (err)
+                        goto err_free_data;
+        }
+
+        /* Configure control GPIOs if available. */
+        if (pdata->ctrl && pdata->num_ctrl > 0) {
+                if (!pdata->speed || pdata->num_speed <= 1) {
+                        err = -EINVAL;
+                        goto err_free_alarm;
+                }
+                err = fan_ctrl_init(fan_data, pdata);
+                if (err)
+                        goto err_free_alarm;
+        }
+
+        err = device_create_file(&pdev->dev, &dev_attr_name);
+        if (err)
+                goto err_free_ctrl;
+
+        /* Make this driver part of hwmon class. */
+        fan_data->hwmon_dev = hwmon_device_register(&pdev->dev);
+        if (IS_ERR(fan_data->hwmon_dev)) {
+                err = PTR_ERR(fan_data->hwmon_dev);
+                goto err_remove_name;
+        }
+
+        dev_info(&pdev->dev, "GPIO fan initialized\n");
+
+        return 0;
+
+err_remove_name:
+        device_remove_file(&pdev->dev, &dev_attr_name);
+err_free_ctrl:
+        if (fan_data->ctrl)
+                fan_ctrl_free(fan_data);
+err_free_alarm:
+        if (fan_data->alarm)
+                fan_alarm_free(fan_data);
+err_free_data:
+        platform_set_drvdata(pdev, NULL);
+        kfree(fan_data);
+
+        return err;
+}
+
+static int __devexit gpio_fan_remove(struct platform_device *pdev)
+{
+        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
+
+        hwmon_device_unregister(fan_data->hwmon_dev);
+        device_remove_file(&pdev->dev, &dev_attr_name);
+        if (fan_data->alarm)
+                fan_alarm_free(fan_data);
+        if (fan_data->ctrl)
+                fan_ctrl_free(fan_data);
+        kfree(fan_data);
+
+        return 0;
+}
+
+#ifdef CONFIG_PM
+static int gpio_fan_suspend(struct platform_device *pdev, pm_message_t state)
+{
+        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
+
+        if (fan_data->ctrl) {
+                fan_data->resume_speed = fan_data->speed_index;
+                set_fan_speed(fan_data, 0);
+        }
+
+        return 0;
+}
+
+static int gpio_fan_resume(struct platform_device *pdev)
+{
+        struct gpio_fan_data *fan_data = platform_get_drvdata(pdev);
+
+        if (fan_data->ctrl)
+                set_fan_speed(fan_data, fan_data->resume_speed);
+
+        return 0;
+}
+#else
+#define gpio_fan_suspend NULL
+#define gpio_fan_resume NULL
+#endif
+
+static struct platform_driver gpio_fan_driver = {
+        .probe          = gpio_fan_probe,
+        .remove         = __devexit_p(gpio_fan_remove),
+        .suspend        = gpio_fan_suspend,
+        .resume         = gpio_fan_resume,
+        .driver = {
+                .name   = "gpio-fan",
+        },
+};
+
+static int __init gpio_fan_init(void)
+{
+        return platform_driver_register(&gpio_fan_driver);
+}
+
+static void __exit gpio_fan_exit(void)
+{
+        platform_driver_unregister(&gpio_fan_driver);
+}
+
+module_init(gpio_fan_init);
+module_exit(gpio_fan_exit);
+
+MODULE_AUTHOR("Simon Guinot <sguinot@lacie.com>");
+MODULE_DESCRIPTION("GPIO FAN driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-fan");